Toussaint, G. and Burov, E. and Avouac, J.-P. (2004) Tectonic evolution of a continental collision zone: A thermomechanical numerical model. Tectonics, 23 (6). Art. No. TC6003. ISSN 0278-7407 http://resolver.caltech.edu/CaltechAUTHORS:20101118-110717109
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We model evolution of a continent-continent collision and draw some parallels with the tectonic evolution of the Himalaya. We use a large-scale visco-plasto-elastic thermomechanical model that has a free upper surface, accounts for erosion and deposition and allows for all modes of lithospheric deformation. For quartz/olivine rheology and 60 mm/yr convergence rate, the continental subduction is stable, and the model predicts three distinct phases. During the phase 1 (120 km or 6% of shortening), deformation is characterized by back thrusting around the suture zone. Some amount of delaminated lower crust accumulates at depth. During phase 2 (120 km–420 km or 6%–22% of shortening), this crustal root is exhumed (medium- to high-grade rocks) along a newly formed major thrust fault. This stage bears similarities with the period of coeval activity of the Main Central thrust and of the South Tibetan Detachment between 20–16 Myr ago. During phase 3 (>420 km or 22% of shortening), the crust is scraped off from the mantle lithosphere and is incorporated into large crustal wedge. Deformation is localized around frontal thrust faults. This kinematics should produce only low- to medium-grade exhumation. This stage might be compared with the tectonics that has prevailed in the Himalaya over the last 15 Myr allowing for the formation of the Lesser Himalaya. The experiment is conducted at constant convergence rate, which implies increasing compressive force. Considering that this force is constant in nature, this result may be equivalent to a slowing down of the convergence rate as was observed during the India-Asia collision.
|Additional Information:||© 2004 American Geophysical Union. Received 3 December 2003; revised 17 August 2004; accepted 15 September 2004; published 30 November 2004. We deeply thank the Associated editor L. Ratschbacher and the reviewers (S. Cloetingh, R. Jamieson, and T. Geria) for constructive comments on the manuscript. We also benefited from discussions with L. Jolivet and L. LePourhiet. Par(o)avoz v7 use engine by A. Poliakov and Y. Podladchikov [Poliakov et al., 1993]. This research was supported in part by the Gordon and Betty Moore Foundation. This is Caltech Tectonic Observatory Contribution 5. This study is not supported by DYETI(INSU-CNRS).|
|Group:||Caltech Tectonics Observatory, Caltech Tectonics Observatory. Indo-Asian Collision Zone|
|Subject Keywords:||continental subduction; numerical modeling; Himalaya; rheology; mountain building|
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|Official Citation:||Toussaint, G., E. Burov, and J.-P. Avouac (2004), Tectonic evolution of a continental collision zone: A thermomechanical numerical model, Tectonics, 23, TC6003, doi:10.1029/2003TC001604|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||18 Nov 2010 21:25|
|Last Modified:||26 Dec 2012 12:39|
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